In-Situ Observation of the Water Distribution in Porous Layers of PEMFCs by Soft X-Ray Radiography

2010 ◽  
Author(s):  
Takashi Sasabe ◽  
Shohji Tsushima ◽  
Shuichiro Hirai
Keyword(s):  
Water Transport ◽  
Temporal Resolution ◽  
Liquid Water ◽  
Water Distribution ◽  
Transport Phenomena ◽  
Catalyst Layer ◽  
In Situ Observation ◽  
X Ray ◽  
Porous Layers ◽  
Liquid Water Transport

To observe the liquid water distribution in porous layers of an operational Proton Exchange Membrane Fuel Cell (PEMFC) with high spatial and temporal resolution, Laboratory-based soft X-ray microscopy has developed. This system can generate low energy X-ray in the soft X-ray range, and maximum sensitivity towards water is achieved. A point X-ray source with a diameter of less than 1.0 μm and the improved detector optics contribute to realize a spatial resolution of 500 nm and a temporal resolution of 1.0 sec/frame. In addition, in-plane and through-plane observations of an operational PEMFC were carried out. In the in-plane observation test, non-uniform distribution of liquid water in the plane of the catalyst layer was observed, and the importance of appropriate design of the catalyst layer to liquid water transport phenomena was suggested. In the through-plane observation test, liquid water discharge behavior near under the rib area was observed, and the importance of channel wall wettability to liquid water transport phenomena was also suggested.

Soft X-ray visualization of the liquid water transport within the cracks of micro porous layer in PEMFC

2011 ◽  
Vol 13 (6) ◽  
pp. 638-641 ◽  
Author(s):  
Takashi Sasabe ◽  
Phengxay Deevanhxay ◽  
Shohji Tsushima ◽  
Shuichiro Hirai
Keyword(s):  
Water Transport ◽  
Porous Layer ◽  
Liquid Water ◽  
X Ray ◽  
Liquid Water Transport

Soft X-Ray Investigation on the Effect of Microstructure of PEMFC Porous Layers on Liquid Water Transport

2011 ◽  
Author(s):  
Takashi Sasabe ◽  
Phengxay Deevanhxay ◽  
Shohji Tsushima ◽  
Shuichiro Hirai
Keyword(s):  
Liquid Water ◽  
Water Distribution ◽  
Water Evaporation ◽  
Carbon Paper ◽  
Carbon Cloth ◽  
Cross Sectional ◽  
X Ray ◽  
Porous Layers ◽  
Water Behavior ◽  
Effect Of Microstructure

In order to investigate the effect of microstructure of PEMFC porous layers on the liquid water behavior, liquid water accumulation and discharge behavior in the operating PEMFC was visualized by soft X-ray radiography. The utilization of low energy X-ray made it possible to detect the liquid water behavior in the porous layers with high temporal and spatial resolution, and the cross-sectional imaging can resolve the each components of the PEMFC. The visualization results showed that the liquid water distribution in the carbon paper and the carbon cloth GDL was completely different. The liquid water in the carbon cloth GDL concentrates at the weaves of fiber bundle and was effectively discharged to the channel. In addition, to investigate the effect of the network of pores in more detail, stereo imaging of the liquid water evaporation process from the carbon paper GDL was carried out. These visualization results suggested that the microstructure of the PEMFC porous layers strongly affect the liquid water behavior in the PEMFC.

Modeling of Liquid Water Transport in Cathode Catalyst Layer of PEM Fuel Cells

2009 ◽  
Author(s):  
Prodip K. Das ◽  
Xianguo Li ◽  
Zhong-Sheng Liu
Keyword(s):  
Water Transport ◽  
Liquid Water ◽  
Catalyst Layer ◽  
Pem Fuel Cells ◽  
Water Flooding ◽  
Dimensionless Time ◽  
Cathode Catalyst ◽  
Water Production ◽  
Cathode Catalyst Layer ◽  
Liquid Water Transport

The performance of a polymer electrolyte membrane (PEM) fuel cell is significantly affected by liquid water generated at the cathode catalyst layer (CCL). Conversely, the ionic conductivity of PEM is directly proportional to its water content; it must have sufficient water. Therefore, it is essential to maintain a delicate water balance, which seems difficult without properly understanding liquid water transport from the CCL. In the present study, a one-dimensional analytical solution of liquid water transport across the CCL is derived from the fundamental transport equations. The effect of CCL wettability on liquid water transport and the effect of liquid water “flooding” on reactant transport have been investigated. It has been observed that hydrophilic characteristic of a CCL plays significant role on the liquid water transport. The liquid water saturation in a hydrophilic CCL can be reduced by increasing the surface wettability or lowering contact angle. Based on a dimensionless time constants analysis, it has been shown that liquid water production from the phase change process is negligible compared to water production from the electrochemical process.

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